An undercurrent of menace is common in L.A., where earthquakes and riots have rattled the palms. But the blast of fear from Benedict Canyon on Aug. 9, 1969, following the murders at 10050 Cielo Drive, was a far grislier terror. Someone was on a gruesome killing rampage, and no one knew why.

The news was sickening: Five people — Sharon Tate, an actress 8 1/2 months pregnant; heiress Abigail Folger; Voytek Frykowski, Folger’s lover; Jay Sebring, a playboy hairstylist; and Steven Parent, a friend of the caretaker — had been coldly stabbed and shot. Tate, 26, the wife of director Roman Polanski, who was abroad, was the last to die. She had begged in vain for the life of her child. The killers had scrawled pig on the door in Tate’s blood.

On Dec. 8, Charles Manson, an ex-con who led a commune near Death Valley, and five members of his ”family” — Susan ”Sexy Sadie” Atkins, Charles ”Tex” Watson, Patricia Krenwinkel, Leslie Van Houten, and Linda Kasabian — were indicted for the Tate murders and for the subsequent killings of grocery-store-chain owners Leno and Rosemary LaBianca. During the trial, a chilling portrait of Manson as a messianic psychopath emerged — along with the revelation that the intended victim had been producer Terry Melcher, the son of Doris Day; he had once lived in the Cielo Drive house with girlfriend Candice Bergen. Manson thought the producer had reneged on getting him a recording contract. (The Beach Boys had recorded a version of Manson’s tune ”Cease to Exist” before the murders.)

Manson, now 58, and four others are serving life sentences. In 1974 the prosecutor, Vincent Bugliosi, published the best-selling Helter Skelter, which was made into a 1976 CBS miniseries about the case. The title comes from a Beatles song that Manson crazily mistook as a call to violence. Polanski, who fled a 1977 conviction of statutory rape in Los Angeles, is in exile in Paris. The house is now rented by Trent Reznor, of the industrial band Nine Inch Nails, who lives and records there. And Angelenos still shudder at the memory of that terrible night — of the hastily bought guns and watchdogs, and of the paranoia wreaked by a 5’2” would-be rock star.